Defroster-heater and baffle installation for refrigerator



March 11, 1958 w. R. MITTENDORF 2,826,047 DEFROSTER-HEATER AND. BAFFLE INSTALLATION I FOR REFRIGERATOR v Filed Dec. 2, 1955 3 Sheets-sheet 1 "mmvron WILLIAM R. MITTENDORF.

Raw/MW ATTORNEYS March 11, 1958 w. R. MITTENDORF 2,826,047

DEFROSTER-HEATER AND BAFFLE INSTALLATION FOR REFRIGERATOR 5 Sheets-Sheet 2 Filed Dec. 2, 1955 I INVENTOR.

WILLIAM R. MITTENDORF. w AWW ATTORNEYS.

"March 1958 w. R. MITTENDORF [3,826,947

DEFROSTER-HEATER AND BAFFLE INSTALLATION FOR REFRIGERATOR 7 Filed Dec. 2, 1955 5 Sheets-Sheet 3 IN VEN TOR.

WILLIAM R. MITTENDORF.

BY MAQW ATTORNEYS United tates Patent DEFROSTER-HEATER AND RAFFLE INSTALLA- TION FOR REFRIGERATUR William R. Mittendorf, Cincinnati, Ohio, assignor to AVCO Manufacturing Corporation, Cincinnati, Ulric, a corporation of Delaware Application December 2, 1955, Serial No. 550,559 2 Claims. 01.62. 102

T his invention relates to a defroster-heater and bathe installation for a refrigerator and, more particularly, to an installation in which effective baffle defrosting can be accomplished, even though there is a considerable variation in spacing between the baffie and the evaporator to which the main portion of the heater is secured.

The present invention finds particular use in a refrigerator having a defroster-heater which is secured adjacent the evaporator of the refrigerator to supply heat thereto during periods when defrosting is desired. An installation of a broadly similar type is disclosed in the Cochran Patent 2,592,394 which issued on April 8, 1952, and is entitled Refrigerator Defrost Product Disposal System." When rigid baffle heater portions of the defroster-heater are used, close dimensional tolerances between the evap orator heater elements and the baffle are necessary to insure thermal contact between the bathe top and the heater. if the distance between the evaporator and the bathe is too great, the heater will not make thermal contact with the battle; whereas, if the bafile-to-evaporator distance is too small, the baffle cannot be installed because of the interference between the heater and the baffle top.

Thus, it is a purpose of this invention to overcome these difficulties by means of a novel, simple and inexpensive construction of the defroster-heater.

Stated briefly, the present invention comprehends the provision of a conventionally insulated refrigerator cabinet having an evaporator in its upper portion forming a frozen food compartment and a lower food compartment separated from the frozen food compartment by a bafile. There is secured to the underside of the evaporator 21 defroster-heater element for melting frost which normally accumulates on the evaporator. One or more portions of the defroster-heater element are yieldably spaced below the evaporator for heating the top surface of the baffle located beneath the evaporator. The baffie not only serves to separate the compartments, but also collects water and ice which fall from the evaporator during the defrosting cycle and directs the water to a discharge point.

It is commonplace for frost to form on the evaporator of a refrigerator, since the air entering the refrigerator when the door is opened contains moisture which deposits and freezes on the relatively cold evaporator. Moisture will likewise be drawn from foodstuffs stored within the refrigerator and be deposited upon the evaporator and freeze thereon. This frost is objectionable, since it acts as a thermal insulator on the evaporator and retardst'ransfe'r of heat to the evaporator from the contents of the refrigerator.

Heat may be applied periodically to melt the frost accumulation. As the frost melts, the water formed drips onto the baffie located below the evaporator. Unless heat is also applied to the bafile during defrosting, the drip water from the evaporator is likely to refreeze on the bathe when normal operation of the refrigeration system is resumed after defrosting. l' uraiermore, since ice the baffle regulates convection currents of air Within the refrigerator and its upper surface is at a temperature generally below-freezing, frost may tend to form on the battle as these currents flow past it. Accumulation of ice on the baffle will tend to interfere with its airflow control characteristics and with its ability to dispose of the defrost products from the evaporator during defrosting. In addition, ice on the baffle may interfere with its removal from the refrigerator and create .an unsightly appearance, which is highly undesirable.

In the present invention the defroster-heater portions which heat the baffle extend either from front to rear or from side to side in the cabinet and are yieldably disposed downwardly to make thermal contact with the top of the bafile, which is made of a heat-conducting material. Thus, there is provided positive thermal contact between the heater and the baille top, irrespective of dimensional variations between the bottom of the evaporator and the baffle top. No bafiie position-adjusting means is required.

Thus, in view of the foregoing, it is an object of the present invention to provide an improved defroster-heat er and baffle installation in a refrigerator.

More specifically, it is an object of the present invention to provide a defroster-heater installation in which a portion of the heater is in intimate contact with the battle, even though departures from ideal dimensions are present.

Another object of the invention is the provision of a defroster-heater installation in which a portion of the heater will be in mechanical and thermal contact with the baffle, despite the fact that the spacing between the evaporator and the bafiie may vary between units produced in large quantity.

A further object of the present invention resides in a defroster-heater installation in which a portion of the, heater is resiliently suspended below the evaporator to make positive contact with the heater portion and the battle, even though variations may exist in the spacing between the evaporator and the battle.

The novel features that I consider characteristic of my invention are set forth in the appended claims; the invention itself, however, both as to its organization and method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in conjunction with the accompanying drawings, in which:

Fig. 1 is a front perspective view of a domestic refrigerator incorporating the present invention;

Fig. 2 is a perspective view of a refrigerator baffle in thermal relationship with two portions of a defrosterheater, an evaporator being shown diagrammatically;

Fig. 3 is a cross-sectional view, taken on plane 33 of Fig. 2, showing the evaporator, part of the defrosterheater associated with the evaporator, and a portion of the heater juxtapositioned with the top of the baffle in their normal operating position;

Fig. 4 is a perspective view similar to Fig. 2, showing an alternate arrangement of the defroster-heater associated with the evaporator (shown diagrammatically) and one portion of the heater in thermal relationship with the bathe; and

Fig. 5 is a cross-sectional view, taken on plane 5--5. of Fig. 4, showing the alternate defroster-heater arrangement.

As illustrated in Figs. 1, 2 and 3, the preferred embodiment of the present invention may be used in a refrigerator cabinet, generally indicated at 163, which is provided with an inner liner 12, which defines an upper freezing compartment closed by access door 14 and a lower food storage compartment 16. A battle, generally indicated at 13, forms a partial thermal barrier between the compartments. A conventional evaporator 20 is provided within the freezing compartment for extraction of heat from the cabinet.

Bafiie i8 is supported at its rear by slots in brackets 22 engaging studs (not shown) carried by the cabinet liner, and at its front by spring clips 24 engaging a projection (not shown) carried by the cabinet liner. To install the bafile, the slots in brackets 22 are engaged with the studs carried by the liner and the front is raised in an arc pivoting about the studs until clips 24 engage the projections carried by the liner. No adjustable positioning means is required for supporting the bafile since, as will be described in more detail later, the dimensional relationship between the evaporator and the bathe is not critic.

To remove frost which has accumulated on the evaporator, a sinuous, electric resistance type defroster-heater 26 is secured directly beneath evaporator 2t as by clips 23. A time clock control is provided in series with thermostats and other control elements (not shown) to periodically supply heater 26 with electrical energy whereby the heater and the bottom surface of the evaporator will be raised in temperature and melt the frost from the evap orator. The specific details of the control system constitute no part of this invention, and are described and claimed in Patent 2,601,466 issued June 24, 1952, to B. D. Thomas, entitled Defroster Circuit.

The specific type of defroster-heater does not constitute a limitation of the present invention, and it should be understood that any defroster-heater, positioned and functioning as does defroster-heater 26, can be used in accordance with the teaching of the present invention.

In the preferred embodiment of the present invention, two forwardly and rearwardly-extendin contact portions 30 and 32 of heater 26 are in firm contact with battle These members are yieldably supported from the evaporator to compensate for the variation in spacing between the evaporator and the baffle. it will be appreciated by those skilled in the art that defroster-heater 26 may, if desired, be a continuous heater in which contact portions 30 and 32 are merely integral parts, or the heater may be made in sections, according to the particular design requirements of the refrigerator.

The bafile 18, as shown in Fig. 8, comprises a heat-conducting top cover 34, which may be made of aluminum, supported by a lower plastic section 36. Cover 34 is also formed to define a peripheral channel which collects drip water falling upon the baffle and directs it to an outlet 40.

Because of dimensional variations in the refrigerator components made in mass production, there is no assurance, with rigid bafile defroster-heaters, that the heater will always be brought into direct physical engagement with the cover of the baffle. Should too much physicai interference be encountered, the bafile would be difficuii or impossible to install; should the heater be spaced too far away from the bafile, there would be insufficient heat transfer to the bafile cover.

To compensate for this variation of spaci between. the bafile and the evaporator without the necessity of providing adjustable baffle-supporting means, this invention contemplates a resilient baiiie defroster-heater. Since the two baflle contact portions of the defroster-heater are similar, a description of the detailed construction of one will suffice.

Contact portion 32 is disposed below the evaporator in contact with the baffle and is joined with torsion portions 42 by connection portions 44. For convenience, contact portion 32 and connection portions is in combination, will be referred to as the bafile defrost portion. The baffle defrost portion is disposed at an acute angle to the horizontal to permit it to yield about the torsion poo tions 42 as the bafile is raised into operating position. The contact portion is spaced below the evaporator a sufficient 4 distance to assure contact with the baflle when the spacing between the evaporator and the bafile is the greatest. As the front of the baffle is raised into position, contact portion 32 will move upwardly in an are about the axes of torsion portions 42. This will impart a restorable twist to torsion portions 42. Thus, contact portions will be in firm contact with the bafiie, due to the force imparted thereto by the torque of the torsion portions attempting to restore the contact members to their original position.

With particular reference to Fig. 2, it is to be observed that the baffle defrost portions are inclined at an acute angle to the horizontal in opposite directions. This permits the baffle to be raised into position without being displaced laterally by the arcuate movement of the baffle defrost portions.

it is to be understood that it is not necessary for all of the resilience to be imparted to the structure by the torsion portions. Connection portions 44 may be deflected by bending movements imparted to them by the upward movement of contact portions 32. Thus, it will be appreciated that the combination of the torsion portions and the connection portions may cooperate to per mit the contact portion to be resiliently displaced by the upward movement of the bafile, at the same time maintaining good thermal contact between the baffle to and the contact portion of the heater.

An alternate construction is illustrated in Figs. 4 and 5. In this embodiment the parallel portions of the serpentine passes of defroster-heater 50 extend from side to side of the evaporator, as contrasted to the passes of the previously described embodiment, which extended from front to rear. One of the passes near the center of the evaporator has a contact portion 32 displaced from the other passes and in intimate thermal contact with baffie top 34. This contact portion is connected to the remainder of the heater by connection portions 54, which are disposed at an acute angle to horizontal. This contact portion, being located near the front-to-rear center of the baflie top cover, which is made of a good heat-conducting material, will raise its temperature sufficiently to melt any ice forming or collecting thereon.

As bafile 18 is installed upwardly into position, a twist will be imparted to contact portion 52 by virtue of its being constrained at both ends by connection portions 54-. This torsion applied to the contact portion will force it into firm thermal contact with the baffle top cover.

It will be apparent, from the previous description of the details of the invention, that there is provided a novel and inexpensive means of securing excellent thermal contact between the defroster-heater and the defrost watercollecting bafiie to compensate for dimensional variations found in mass-produced units.

The various features and advantages of the design and construction disclosed are thought to be clear from the foregoing description. Various other features and advantages, not specifically enumerated, will undoubtedly occur to those versed in the art as, likewise, will many variations and modifications of the preferred embodiment of the invention illustrated, all of which may be achieved without departing from the spirit and scope of the invention.

Having described a preferred and alternate embodiment of my invention, I claim:

1. In combination, a refrigerator cabinet, an evaporator within said cabinet, a serpentine defroster-heater secured to and beneath said evaporator, said heater comprising a main section lying in a plane and secured to said evaporator, at least two parallel heater portions forming a contact section spaced below said main section, torsion members integral and continuous with said main section and lying in the plane of said main section, connecting members extending between said torsion members and said contact section, said connecting members being inclined less than to the plane of said main section, a defrost water-collecting bafiie, means sup- 2,826,047 5 6 porting said baffle in said cabinet beneath said evaporator, movement generally upwardly into engagement with said said support means maintaining said bafile in engagement contact section. with said contact section to resiliently stress said torsion members, thereby urging said contact section tightly References Cited in the fil f this patent against said baffle.

5 2. The combination according to claim 1 in which said UNITED STATES PATENTS support means mounts said bafiie in said refrigerator for 2,592,394 Cochran Apr. 8, 1952 

